Increased public interest in food safety and clean agriculture (e.g., ecological agriculture, organic culture and agrochemical-free cultivation) is driving a production system change from dependence on and use of agrochemicals toward their elimination. However, this raises a huge time- and labor-consuming problem with weeds. The weeding robot “TAMBA” decreases weeds in paddy fields without resorting to herbicides. ”TAMBA” autonomously travels while avoiding rice plant rootstocks. Final goal is to runs on schedule, return to dock and recharge like “ROOMBA”. In this time, we studied an image processing system on the weeding robot “TAMBA” that judges a line of rice plants in an ideal environment that only rice plants grew on a paddy field.